CDMA2000 is a third-generation (3G) wireless communications standard that uses Code Division Multiple Access (CDMA) to facilitate wireless communications between CDMA base stations and mobile devices. Variants of CDMA2000 include CDMA2000 1x, which provides both voice and data services over a standard CDMA channel, and CDMA2000 Evolution Data-Optimized (1xEV-DO) which is optimized for High Data Rate (HDR) capability. CDMA2000 1xEV-DO Revision B defines a multicarrier system providing peak transmission rates of 73.5 Mbps in the forward link and 27 Mbps in the reverse link by aggregating multiple 1.25 MHz carrier within 20 MHz of bandwidth. Current versions of the CDMA2000 standards are published and approved by the Telecommunications Industry Association and the International Telecommunication Union.
FIG. 1 illustrates exemplary forward link channel structures for use in a CDMA2000 multicarrier system. A base transceiver system 10 provides wireless services through a CDMA2000 1x carrier, which is optimized for voice and data communications, and two CDMA2000 1xEV-DO carriers, which are optimized for high speed data communications. The CDMA2000 1x carrier includes a forward link channel structure 20 which is separated into a plurality of logical channels, each encoded with a unique Walsh code. In operation, a mobile station 12 establishes communication on the CDMA2000 1x carrier 20 by first locating pilot channel 22. After the pilot channel 22 is acquired, the mobile station 12 locates the sync channel 24 which is used for providing synchronization and configuration information to the mobile station 12. Paging channels 26 provide CDMA2000 1x control and paging messages to the mobile station 12. The traffic channels 28 are used for voice and data communications on the CDMA2000 1x carrier 20.
The CDMA2000 1xEV-DO carriers are optimized for high speed data communications and include forward link channels 30 and 40, respectively. Each forward link channel 30 and 40 includes time slots allocated for pilot channels for system acquisition, and control channels for providing control information to mobile stations. In operation, the mobile station 12 separately acquires the pilot and control channels for each 1xEV-DO carrier to set up wireless communications on the respective carrier.
The base transceiver system 10 allocates wireless resources, such as time slots on the 1xEV-DO carriers, to the mobile station 12 based on the mobile user's Quality of Service (QoS) characteristics. A mobile station with high QoS characteristics may be given priority over other mobile stations to ensure data communications to the mobile station are delivered at a high data rate, for example by assigning additional time slots on both forward link channels 30 and 40. As the number of active mobile users increases, the resources available for each user decreases, leading to a decrease in the quality of service experienced by many mobile stations. It is thus desirable to maximize sector throughput in a multicarrier environment to increase overall quality of service.